1. Field of Invention
This invention relates to improvements in apparatus for transmitting torque in power trains by way of a hydrokinetic torque converter which is equipped with a bypass or lockup clutch and, more particularly, to improvements in transmitting torque by way of a hydrokinetic torque converter which can transmit torque by way of a turbine and/or by way of a bypass or lockup clutch constructed and assembled to operate in parallel with such turbine. Still more particularly the present invention relates to an improved apparatus and method utilized in the construction and assembly of such a torque converter, which reduces the complexity, the weight, the space requirements, and manufacturing costs of the torque transmitting apparatus.
As a general rule, a hydrokinetic torque converter which can be utilized in accordance with the present apparatus and method comprises an impeller or hydraulic pump, a turbine, a stator, and a housing, which is driven by the rotary output element of a prime mover (such as the engine of a motor vehicle), and serves to transmit torque to the hydraulic pump. The housing is coaxial with the pump and with the turbine and defines an interior chamber, which accommodates the turbine as well as a bypass clutch or lockup clutch cooperating with a torsion damper including an input element and an output element whose torque capacity (i.e. the maximum torque which the damper can transmit) is less than the nominal (i.e. maximum achievable) torque of the prime mover. The damper prevents the transmission of any appreciable oscillations of torque from the output element of the engine of the motor vehicle to the input shaft of the transmission while the motor vehicle is operated within the main driving range.
The bypass clutch or lockup clutch serves merely to operate with slip in order to compensate for peaks of oscillations of the torque that is being transmitted by the output element of the engine. When the operation of the motor vehicle is within the main driving range as well as when the bypass clutch is operated with slip, undesirable fluctuations of torque cannot be transmitted to the input element of the transmission by the expedient of reducing the magnitude of the torque which can be transmitted by the clutch. Such pronounced fluctuations of torque are likely to develop, for example, due to resonance, to an abrupt change of the load and/or for certain other reasons.
Such a bypass or lockup clutch can include a friction clutch having a first friction surface on a substantially radially extending portion of the housing and a second friction surface provided on an axially displaceable piston which is movable in the direction of the turbine to move its friction surface into or away from frictional engagement with the first friction surface such that the magnitude of torque, which the clutch can transmit, depends on the extent of frictional engagement between the first and second surfaces. The second friction surface is normally provided on a radially outer portion of the piston, and the radially inner portion of such piston can transmit torque directly to the turbine or to the rotary input element of a transmission, which receives torque from the turbine or a driven hub which is separably connected to the turbine.
2. Description of Related Art
Under the current state of the art, the connection between the output element of the torsion damper and the hub driven by the turbine is either made by mating internal and external splines or as a riveted joint. This has the inherent disadvantages of the rather expensive and time consuming manufacturing processes required to machine the mating splines and/or requires numerous component parts and/or other fasteners and related labor costs to install the damper in the torque converter.
Hydrokinetic torque converters of the above-outlined character are disclosed, for example, in U.S. Pat. Nos. 5,029,087 and 4,577,737 recited herein, and also disclosed in U.S. Pat. No. 5,752,894, which is commonly owned and incorporated herein by reference.